﻿using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Drawing;

public partial class ValidateCode : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        this.CreateCheckCodeImage(GenerateCheckCode());
    }

    private string GenerateCheckCode()
    {
        string codeSerial = "1,2,3,4,5,6,7,8,9,0";
        string[] arr = codeSerial.Split(',');
        string checkCode = "";
        int randValue = -1;
        Random rand = new Random(unchecked((int)DateTime.Now.Ticks));
        int codeLen = 4;//长度
        System.Random random = new Random();
        for (int i = 0; i < codeLen; i++)
        {
            randValue = rand.Next(0, arr.Length - 1);

            checkCode += arr[randValue];
        }


        Response.Cookies.Add(new HttpCookie("ValidateCode", checkCode));

        return checkCode;
    }

    private void CreateCheckCodeImage(string checkCode)
    {
        if (checkCode == null || checkCode.Trim() == String.Empty)
            return;

        System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 20);
        Graphics g = Graphics.FromImage(image);

        try
        {
            //生成随机生成器
            Random random = new Random();

            //清空图片背景色
            g.Clear(Color.White);


            string[] fonts = { "Arial", "Comic Sans MS", "Tahoma", "Verdana" };

            Font font = new System.Drawing.Font(fonts[random.Next(0, fonts.Length)], 12, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));

            System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.FromArgb(random.Next(255), random.Next(255), random.Next(255)), Color.FromArgb(random.Next(255), random.Next(255), random.Next(255)), 1.2f, true);

            g.DrawString(checkCode, font, brush, 2, 2);

            //画图片的前景噪音点
            for (int i = 0; i < 25; i++)
            {
                int x = random.Next(image.Width);
                int y = random.Next(image.Height);

                image.SetPixel(x, y, Color.FromArgb(random.Next()));
            }

            //画图片的边框线
            g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);

            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
            Response.ClearContent();
            Response.ContentType = "image/Gif";
            Response.BinaryWrite(ms.ToArray());
        }
        finally
        {
            g.Dispose();
            image.Dispose();
        }
    }
}
